Converting Frames page to iframe

I have my website is a frame based site, and I want to change to iframe as frames are going to be deprecated soon (It is already not supported in HTML5), I know it is not one to one transfer, but I do not see how it is possible to define columns and rows, my old frame page is:

The output of the iframe is horrible were the header.php which is in the logo iframe is not appearing at the top edge of the screen but at the upper third, also the login.php is not shown in the fully but truncated,
Unfortunately using the other alternative (<div>) is not an option for as I am using for different pages different css (as some of them are ready to use to pages) and redesigning the css is a lot of work that is why I am thinking in the iframe), can some one help me please?

You want the header frame to be on the top right?
Just change the width of the top frame to 68%

Change main frame to 100% width

...but you are still using an old fashioned way of making a site, you are going from frames to iframes which is just as bad.
Use iframes for small bits of code you may want to show, e.g. a news feed. They shouldn't be used to design a site

Unfortunately using the other alternative (<div>) is not an option for as I am using for different pages different css

Agree with GaryC123. You should redesign the site. Also, you may want to check the code meticulously. Spelling errors are usually just ignored. Example: hight="10%" should probably be height="10%" if it is to have any effect.

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